Method of sharing a UE receiver between D2D and cellular operations based on activity

ABSTRACT

Systems and methods are disclosed for utilizing non-overlapping time periods within one or more Discontinuous Reception (DRX) cycles configured for a Device-to-Device (D2D) capable wireless device for different types of operations. In some embodiments, these different types of operations are cellular and D2D operations such that the D2D capable wireless device performs cellular and D2D operations (e.g., reception of cellular and D2D signals) during non-overlapping time periods during one or more DRX cycles. In this manner, a D2D capable wireless device that, for example, can only receive one type of signal at a time is enabled to receive both cellular and D2D signals.

RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationSer. No. 62/035,664, filed Aug. 11, 2014, the disclosure of which ishereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of wirelesscommunication, and more specifically to methods of sharing a UserEquipment device (UE) receiver between Device-to-Device (D2D) andcellular operations.

BACKGROUND

Device-to-Device (D2D) communication in a cellular communicationsnetwork is receiving a significant amount of interest, particularly withrespect to next and future generation networks. D2D communication iscommunication between a source device and a target device, where boththe source device and the target device are wireless devices (e.g., UserEquipment devices (UEs) in 3^(rd) Generation Partnership Project (3GPP)terminology). Some of the potential advantages of D2D communicationinclude off-loading of the cellular network, faster communication,increased awareness of surrounding wireless devices of interest (e.g.,running the same application), higher-quality links due to a shorterdistance, etc. Some appealing applications of D2D communications arevideo streaming, online gaming, media downloading, Peer-to-Peer (P2P),file sharing, etc.

A D2D capable wireless device (e.g., a D2D capable UE) may besimultaneously configured to: (1) receive cellular signals on theDownlink (DL) carrier frequency and (2) receive D2D signals of other D2Dcapable wireless devices on the Uplink (UL) carrier frequency. The ULand DL carrier frequencies may belong to the same frequency band or todifferent frequency bands. The D2D capable wireless device may not beable to simultaneously receive both types of signals (i.e., cellularsignals and D2D signals) due to a limited amount of receiver resourcesat the D2D capable wireless device. A receiver resource is characterizedby radio front end resources (e.g., a Radio Frequency (RF) poweramplifier, RF filters, etc.) and/or baseband resources (e.g.,processors), memory, etc. This results in a scenario where the D2Dcapable wireless device can effectively use its receiver resources foronly one of the two types of operations at a given time, i.e., the D2Dcapable wireless device can use its receiver resources for either D2Doperation or for cellular operation at a given time.

The ability to receive only DL cellular signals or only D2D signals at agiven time degrades the overall system performance. For example, the D2Dcapable wireless device may miss scheduling of data on a cellular linkwhile receiving D2D signals. A network node (e.g., the serving basestation of the D2D capable wireless device) will be unaware of the factthat D2D capable wireless device has missed certain data blocks on thecellular link due to D2D reception. Therefore, such missed packets/datablocks will be retransmitted to the D2D capable wireless device aftermissed reception is detected by the higher layer protocols, e.g. RadioLink Control (RLC), Internet Protocol (IP), etc. This increases thepacket transmission delay and also degrades the link adaptation of thecellular DL scheduling channel (e.g., Physical Downlink Control Channel(PDCCH)). To compensate for the missed PDCCH, the network may increasethe resources for PDCCH (e.g., control channel elements and/or transmitpower). This in turn will consume more resources for PDCCH and will inturn reduce cellular DL capacity and/or increase interference on thoseresource elements.

In light of the discussion above, systems and methods are needed toavoid or minimize the loss of reception of data by a D2D capablewireless device on a cellular link as well as on a D2D link.

SUMMARY

Systems and methods are disclosed for utilizing non-overlapping timeperiods within one or more Discontinuous Reception (DRX) cyclesconfigured for a Device-to-Device (D2D) capable wireless device fordifferent types of operations. In some embodiments, these differenttypes of operations are cellular and D2D operations such that the D2Dcapable wireless device performs cellular and D2D operations (e.g.,reception of cellular and D2D signals) during non-overlapping timeperiods during one or more DRX cycles. In this manner, a D2D capablewireless device that, for example, can only receive one type of signalat a time is enabled to receive both cellular and D2D signals.

In some embodiments, a wireless device enabled to operate in a cellularcommunications network is configured to, or operable to, determine afirst time period within a DRX cycle for cellular operation and a secondtime period within a DRX cycle for D2D operation, where the first timeperiod and the second time period are non-overlapping time periods. Thewireless device is further configured to perform a D2D operation duringthe first time period and a cellular operation during the second timeperiod.

In some embodiments, the determination of the first time period and thesecond time period comprises one or more of: determining the first timeperiod and the second time period based on a predefined rule,determining the first time period and the second time periodautonomously, determining the first time period and the second timeperiod based on a message received from another node, determining thefirst time period and the second time period based on a configurationreceived via higher-layer signaling, adapting one or both of the firsttime period and the second time period, and configuring one or both ofthe first time period and the second time period.

In some embodiments, the first time period is one of a DRX ON durationand a DRX OFF duration during a DRX cycle, and the second time period isanother one of the DRX ON duration and the DRX OFF duration during thesame DRX cycle.

In some embodiments, the wireless device is configured with a DRX cyclefor Downlink (DL) cellular operation, the first time period is a DRX ONduration of the DRX cycle for DL cellular operation, and the second timeperiod is a DRX OFF duration of the DRX cycle for DL cellular operation.

In some embodiments, the wireless device is configured with a common DRXcycle for both DL cellular operation and D2D operation, the first timeperiod is one of a DRX OFF duration and a DRX ON duration of the commonDRX cycle, and the second time period is another one of the DRX ONduration and the DRX OFF duration of the common DRX cycle. In someembodiments, the first time period is the DRX ON duration of the commonDRX cycle, and the second time period is the DRX OFF duration of thecommon DRX cycle.

In some embodiments, the first time period is a first DRX ON duration ofa first DRX cycle, and the second time period is a second DRX ONduration of a second DRX cycle.

In some embodiments, the first time period and the second time periodare non-overlapping time periods within a DRX ON duration of a DRXcycle. In some embodiments, an amount of time during the DRX ON durationused for the first time period and an amount of time during the DRX ONduration used for the second time period are network configured. In someembodiments, an amount of time during the DRX ON duration used for thefirst time period and an amount of time during the DRX ON duration usedfor the second time period are decided by the wireless deviceautonomously.

In some embodiments, the first time period and the second time periodare configured such that the first time period and the second timeperiod are separated in time by a time (t) for which one or both of thefollowing conditions hold:Tmin≦t≦Tmax,where Tmin is a predefined minimum amount of time and Tmax is apredefined maximum amount of time.

In some embodiments, the first time period and the second time periodare configured such that a predefined order is maintained between thefirst time period and the second time period.

In some embodiments, the D2D operation performed during the first timeperiod is reception of D2D signals, and the cellular operation performedduring the second time period is reception of DL cellular signals.

In some embodiments, the first and second time periods are within thesame DRX cycle. In some embodiments, the DRX cycle is one of a DLcellular DRX cycle and a common DRX cycle for both DL cellular and D2Doperation.

In some embodiments, the first and second time periods are withindifferent DRX cycles. In some embodiments, each of the different DRXcycles is one of a DL cellular DRX cycle and a common DRX cycle for bothDL cellular and D2D operation.

Embodiments of a method of operation of a wireless device are alsodisclosed.

Embodiments of a network node of a cellular communications network arealso disclosed. In some embodiments, the network is configured, oroperable to, determine one or more DRX sharing rules for a wirelessdevice, where the one or more DRX sharing rules define non-overlappingtime periods within one or more DRX cycles to be used by the wirelessdevice for cellular and D2D operations. The network node is furtherconfigured to configure the wireless device with the one or more DRXsharing rules.

In some embodiments, the network node is further operable to dynamicallyadapt the one or more DRX sharing rules for the wireless device.

In some embodiments, the non-overlapping time periods comprise a firsttime period for cellular operation and a second time period for D2Doperation, and the one or more DRX sharing rules comprise a rule thatthe first time period is one of a DRX ON duration and a DRX OFF durationduring a DRX cycle and the second time period is another one of the DRXON duration and the DRX OFF duration during the same DRX cycle.

In some embodiments, the non-overlapping time periods comprise a firsttime period for cellular operation and a second time period for D2Doperation, and the one or more DRX sharing rules comprise a rule thatthe first time period is a first DRX ON duration of a first DRX cycleand the second time period is a second DRX ON duration of a second DRXcycle.

In some embodiments, the non-overlapping time periods comprise a firsttime period for cellular operation and a second time period for D2Doperation, and the one or more DRX sharing rules comprise a rule thatthe first time period and the second time period are non-overlappingtime periods within a DRX ON duration of a DRX cycle.

In some embodiments, the non-overlapping time periods comprise a firsttime period for cellular operation and a second time period for D2Doperation, and the one or more DRX sharing rules comprise a rule thatthe first time period and the second time period are configured suchthat the first time period and the second time period are separated intime by a time (t) for which one or both of the following conditionshold:Tmin≦t≦Tmax,where Tmin is a predefined minimum amount of time and Tmax is apredefined maximum amount of time.

In some embodiments, the non-overlapping time periods comprise a firsttime period for cellular operation and a second time period for D2Doperation, and the one or more DRX sharing rules comprise a rule thatthe first time period and the second time period are configured suchthat a predefined order is maintained between the first time period andthe second time period. In some embodiments, the network node determinesthe one or more DRX sharing rules for the wireless device based on oneor more criteria, the one or more criteria comprising at least one of agroup consisting of: an amount of cellular and/or D2D traffic, batterylife and/or power consumption of the wireless device, DRX cycle length,length of ON duration, occasions of D2D operations, receiver capabilityof the wireless device, and activity state of the wireless device.

In other embodiments, a network node is configured to, or operable to,determine that a wireless device is configured or is being configured inDRX for receiving D2D and/or cellular signals; determine that thewireless device is sharing or is expected to share time during one ormore DRX cycles for D2D operation and cellular operation; and, upondetermining that the wireless device is configured or is beingconfigured in DRX for receiving D2D and/or cellular signals anddetermining that the wireless device is sharing or is expected to sharetime during one or more DRX cycles for D2D operation and cellularoperation, adapt an existing DRX cycle configuration or configure a newDRX cycle to enable the wireless device to share time during one or moreDRX cycles for D2D operation and cellular operation.

In some embodiments, adaptation of the existing DRX cycle configurationor configuration of a new DRX cycle comprises adaptation of a DRX ONduration of the one or more DRX cycles.

In some embodiments, the adaptation of the existing DRX cycleconfiguration or configuration of a new DRX cycle is based on one ormore criteria comprising of at least occasions of D2D operations.

In some embodiments, adaptation of the existing DRX cycle configurationor configuration of a new DRX cycle comprises adaptation of at least oneof a predefined minimum amount of time and a predefined maximum amountof time between non-overlapping time periods within one or more DRXcycles for D2D and cellular operations.

In some embodiments, adaptation of the existing DRX cycle configurationor configuration of a new DRX cycle comprises adaptation of an orderingof non-overlapping time periods within one or more DRX cycles for D2Dand cellular operations.

Embodiments of a method of operation of a network node are alsodisclosed.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the embodiments in association withthe accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 illustrates direct Device-to-Device (D2D) communication betweentwo wireless devices via a direct D2D link in a cellular communicationsnetwork;

FIG. 2 illustrates locally routed D2D communication between two wirelessdevices via a locally routed D2D link in a cellular communicationsnetwork;

FIG. 3 illustrates conventional cellular communication between twowireless devices in a cellular communications network;

FIG. 4 illustrates one example of a D2D architecture for a cellularcommunications network;

FIG. 5 illustrates one example of Discontinuous Reception (DRX) in LongTerm Evolution (LTE);

FIGS. 6 through 8 graphically illustrate sharing non-overlapping timeperiods of DRX for cellular and D2D operations according to someembodiments of the present disclosure;

FIG. 9 is a flow chart that illustrates the operation of a wirelessdevice to perform DRX sharing for cellular and D2D operations accordingto some embodiments of the present disclosure;

FIG. 10 is a flow chart that illustrates the operation of a network nodeto configure a wireless device for DRX sharing according to someembodiments of the present disclosure;

FIG. 11 is a flow chart that illustrates the operation of a network nodeto adapt DRX to enable DRX sharing by a wireless device for D2D andcellular operations according to some embodiments of the presentdisclosure;

FIG. 12 illustrates the operation of a wireless device to transmitcapability information related to the DRX sharing according to someembodiments of the present disclosure;

FIGS. 13 and 14 illustrate embodiments of a wireless device; and

FIGS. 15 and 16 illustrate embodiments of a base station.

DETAILED DESCRIPTION

The embodiments set forth below represent information to enable thoseskilled in the art to practice the embodiments and illustrate the bestmode of practicing the embodiments. Upon reading the followingdescription in light of the accompanying drawing figures, those skilledin the art will understand the concepts of the disclosure and willrecognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure and the accompanying claims.

In the following description, numerous specific details are set forth.However, it is understood that embodiments of the disclosure may bepracticed without these specific details. In other instances, well-knowncircuits, structures, and techniques have not been shown in detail inorder not to obscure the understanding of this description. Those ofordinary skill in the art, with the included descriptions, will be ableto implement appropriate functionality without undue experimentation.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc. indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to implement such feature, structure, orcharacteristic in connection with other embodiments whether or notexplicitly described.

In the following description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. It should beunderstood that these terms are not intended as synonyms for each other.“Coupled” is used to indicate that two or more elements, which may ormay not be in direct physical or electrical contact with each other,cooperate or interact with each other. “Connected” is used to indicatethe establishment of communication between two or more elements that arecoupled with each other.

The present disclosure relates to systems and methods for utilizingnon-overlapping time periods within one or more Discontinuous Reception(DRX) cycles configured for a Device-to-Device (D2D) capable wirelessdevice (also referred to herein as a D2D wireless device or sometimes aD2D User Equipment device (UE)) for cellular and D2D operations. Beforeproceeding, a description of some terminology that is used throughoutthis disclosure is beneficial.

An electronic device (e.g., an end station or a network device) storesand transmits (internally and/or with other electronic devices over anetwork) code (composed of software instructions) and data usingmachine-readable media, such as non-transitory machine-readable media(e.g., machine-readable storage media such as magnetic disks, opticaldisks, read only memory, flash memory devices, and phase change memory)and transitory machine-readable transmission media (e.g., electrical,optical, acoustical, or other form of propagated signals—such as carrierwaves and infrared signals). In addition, such electronic devicesinclude hardware such as a set of one or more processors coupled to oneor more other components, such as one or more non-transitorymachine-readable media (to store code and/or data), user input/outputdevices (e.g., a keyboard, a touchscreen, and/or a display), and networkconnections (to transmit code and/or data using propagating signals).The coupling of the set of processors and other components is typicallythrough one or more busses and bridges (also termed as bus controllers).Thus, a non-transitory machine-readable medium of a given electronicdevice typically stores instructions for execution on one or moreprocessors of that electronic device. One or more parts of an embodimentof the disclosure may be implemented using different combinations ofsoftware, firmware, and/or hardware.

As used herein, a network device or apparatus (e.g., a router, a switch,or a bridge) is a piece of networking equipment, including hardware andsoftware, which communicatively interconnects other equipment on thenetwork (e.g., other network devices and end stations). Some networkdevices are “multiple services network devices” that provide support formultiple networking functions (e.g., routing, bridging, switching, Layer2 aggregation, session border control, Quality of Service (QoS), and/orsubscriber management), and/or provide support for multiple applicationservices (e.g., data, voice, and video). Subscriber end stations (e.g.,servers, workstations, laptops, netbooks, palm tops, mobile phones,smartphones, multimedia phones, Voice over Internet Protocol (VoIP)phones, UE, terminals, portable media players, Global Positioning System(GPS) units, gaming systems, and set-top boxes) access content/servicesprovided over the Internet and/or content/services provided on VirtualPrivate Networks (VPNs) overlaid on (e.g., tunneled through) theInternet. The content and/or services are typically provided by one ormore end stations (e.g., server end stations) belonging to a service orcontent provider or end stations participating in a Peer-to-Peer (P2P)service, and may include, for example, public webpages (e.g., freecontent, store fronts, or search services), private webpages (e.g.,username/password accessed webpages providing email services), and/orcorporate networks over VPNs. Typically, subscriber end stations arecoupled (e.g., through customer premise equipment coupled to an accessnetwork (wired or wirelessly)) to edge network devices, which arecoupled (e.g., through one or more core network devices) to other edgenetwork devices, which are coupled to other end stations (e.g., serverend stations). One of ordinary skill in the art will realize that anynetwork device, end station, or other network apparatus can perform thefunctions described herein.

D2D: As used herein, the terms D2D, Proximity Service (ProSe), and even“P2P” communication may be used interchangeably.

D2D Device: As used herein, a D2D device, or interchangeably called aD2D wireless device or D2D UE in some embodiments herein, is any devicecapable of at least receiving or transmitting radio signals on a directradio link, i.e., between the D2D device and another D2D device orentity. A D2D device (or D2D-capable device) may also be comprised in acellular UE, a Personal Digital Assistant (PDA), a laptop, a mobilephone, a sensor, a relay, a D2D relay, or even a small base station(e.g., a low power or small cell base station) employing a UE-likeinterface. A D2D device, or D2D-capable device, is able to support atleast one D2D operation.

D2D Operation: As used herein, a D2D operation may comprise any actionor activity related to D2D, e.g., transmitting or receiving asignal/channel type for D2D purposes, transmitting or receiving data bymeans of D2D communication, transmitting or receiving control orassistance data for D2D purposes, transmitting or receiving a requestfor control or assistance data for D2D, selecting a D2D operation mode,initiating/starting D2D operation, switching to a D2D operation modefrom a cellular operation mode, or configuring a receiver or atransmitter with one or more parameters for D2D. D2D operation may befor a commercial purpose or to support public safety, using the datarelated to D2D. D2D operation may or may not be specific to a certainD2D service.

D2D Receive Operation: As used herein, a D2D receive operation may becomprised in a D2D operation which may, in one example, also involveother than D2D receive operations.

Cellular Operation: As used herein, a cellular operation (by a wirelessdevice or UE) may comprise any action or activity related to a cellularnetwork (any one or more Radio Access Technologies (RATs)). Someexamples of a cellular operation may be a radio signal transmission, aradio signal reception, performing a radio measurement, and performing amobility operation or Radio Resource Management (RRM) related to acellular network.

D2D Transmission: As used herein, a D2D transmission is any transmissionby a D2D device. Some examples of D2D transmission are physical signalsor physical channels, dedicated or common/shared signals, e.g., areference signal, a synchronization signal, a discovery channel, acontrol channel, a data channel, a broadcast channel, a paging channel,Scheduling Assignment (SA) transmissions, etc. A D2D transmission on adirect radio link is intended for receiving by another D2D device. A D2Dtransmission may be a unicast, groupcast, or broadcast transmission. AD2D transmission may be on the Uplink (UL) time-frequency resources of awireless communication system.

Coordinating Node: As used herein, a coordinating node is a node thatschedules; decides, at least in part; or selects time-frequencyresources to be used for at least one of: cellular transmissions and D2Dtransmissions. The coordinating node may also provide the schedulinginformation to another node such as another D2D device, a cluster head,a radio network node such as an enhanced or evolved Node B (eNB), or anetwork node (e.g., a core network node). The coordinating node maycommunicate with a radio network node.

Radio Spectrum: Although at least some of the embodiments are describedfor D2D transmissions in the UL spectrum (e.g., Frequency DivisionDuplexing (FDD)) or UL resources (e.g., Time Division Duplexing (TDD)),the embodiments disclosed herein are not limited to the usage of ULradio resources, neither to licensed nor unlicensed spectrum, or anyspecific spectrum at all.

Cellular Network: A cellular network, which is interchangeably referredto herein as a cellular communications network, may comprise, e.g., aLong Term Evolution (LTE) network (e.g., FDD or TDD), a UniversalTerrestrial Radio Access (UTRA) network, a Code Division Multiple Access(CDMA) network, WiMAX, a Global System for Mobile Communications (GSM)network, or any network employing any one or more RATs for cellularoperation. The description of many of the embodiments provided hereinfocuses on LTE and, as such, LTE terminology is oftentimes used;however, the embodiments described herein are not limited to the LTERAT.

RAT: Example RATs include, e.g., LTE (FDD or TDD), GSM, CDMA, WidebandCDMA (WCDMA), WiFi, Wireless Local Area Network (WLAN), WiMAX, etc.

Network Node: As used herein, a network node may be a radio network nodeor another network node. Some examples of a radio network node are aradio base station, a relay node, an access point, a cluster head, aRadio Network Controller (RNC), etc. The radio network node is comprisedin a wireless communications network and may also support cellularoperation. Some examples of a network node which is not a radio networknode include a core network node, a Mobility Management Entity (MME), anode controlling at least in part mobility of a wireless device, aSelf-Organizing Network (SON) node, an Operations and Maintenance (O&M)node, a positioning node, a server, an application server, a D2D server(which may be capable of some but not all D2D-related features), a nodecomprising a ProSe function, a ProSe server, an external node, or a nodecomprised in another network.

Multiple Carrier Frequencies: Multiple carrier frequencies may refer toany combination of: different carrier frequencies within the samefrequency band or within different frequency bands, the same Public LandMobile Network (PLMN) or different PLMNs, and the same RAT or differentRATs. D2D operation may or may not occur on dedicated carrierfrequencies. Downlink (DL) and UL carrier frequencies in FDD are alsoexamples of different carrier frequencies. A frequency band herein maybe FDD, TDD, Half Duplex FDD (HD-FDD), or even unidirectional (e.g., aDL-only band such as Band 29, in some examples).

D2D Communication: As used herein, D2D communication is communicationover a D2D link between at least a source D2D device and a target D2Ddevice. The D2D communication may be over a direct D2D link between thesource and destination D2D devices or over a locally routed D2D linkbetween the source and destination D2D devices.

Direct D2D Link: As used herein, a direct D2D link is a link between asource D2D device and a target D2D device that does not pass through anyintermediate nodes (i.e., the link is directly from the source D2Ddevice to the target D2D device) (see FIG. 1 as an example).

Locally Routed D2D Link: As used herein, a locally routed D2D link is alink between a source D2D device and a target D2D device that passesthrough a common radio access node without passing through the corenetwork (see FIG. 2 as an example).

FIGS. 1 and 2 illustrate examples of D2D communication in a cellularcommunications network 10. In contrast, FIG. 3 illustrates conventionalcommunication between two wireless devices in the cellularcommunications network 10. Specifically, as illustrated in FIGS. 1through 3, the cellular communications network 10 includes a RadioAccess Network (RAN) 12 (e.g., an Enhanced or Evolved UniversalTerrestrial Radio Access Network (E-UTRAN)) and a core network 14 (e.g.,an Enhanced or Evolved Packet Core (EPC)). The RAN 12 includes a numberof base stations 16, which in 3^(rd) Generation Partnership Project(3GPP) LTE are eNBs. Note that the base stations 16 are only examples ofnodes in the RAN 12, which are referred to herein as radio network nodesor radio access nodes. Other examples of radio network nodes includeRemote Radio Heads (RRHs), etc. The core network 14 includes a number ofcore network nodes, which in this example include a Serving Gateway(SGW)/Packet, or Packet Data Network, Gateway (PGW) 18.

FIG. 1 illustrates direct D2D communication (i.e., a direct data path)between two wireless devices 20 (e.g., UEs) via a direct D2D link. Incontrast, FIG. 2 illustrates locally routed D2D communication betweenthe two wireless devices 20 via a locally routed D2D link. As shown, thelocally routed D2D communication is routed through the base station 16without passing through the core network 14. In other words, a D2Dtransmission (i.e., the data path) from one of the wireless devices 20is transmitted from that wireless device 20 to the base station 16 andthen transmitted from the base station 16 to the other wireless device20 without passing through the core network 14. In contrast to the D2Dcommunication of FIGS. 1 and 2, FIG. 3 illustrates conventional cellularcommunication between the two wireless devices 20 where a transmissionfrom the source wireless device 20 is transmitted from the sourcewireless device 20 to the base station 16 serving the source wirelessdevice 20, from the base station 16 serving the source wireless device20 through the core network 14 to the base station 16 serving the targetor destination wireless device 20, and then from the base station 16serving the target or destination wireless device 20 to thetarget/destination wireless device 20.

An example of a D2D architecture including the interfaces between thevarious nodes is illustrated in FIG. 4. In this example, thearchitecture is a 3GPP LTE architecture and, as such, LTE terminology isused. As illustrated, the UEs 20 are connected to the E-UTRAN 12 viacorresponding LTE-Uu interfaces. The E-UTRAN 12 is connected to the EPC14 via an S1 interface. The UEs 20 include ProSe Applications (APPs) 22that enable D2D communication between the UEs 20 via a direct D2D link.This direct D2D link is provided via an interface referred to in FIG. 4as a PC5 interface. The direct D2D link may use uplink time and/orfrequency resources of the E-UTRAN 12, DL time and/or frequencyresources of the E-UTRAN 12, or time and/or frequency resources that arenot utilized by the E-UTRAN 12 (e.g., an unlicensed spectrum). In thisexample, one of the UEs 20 is also connected to a ProSe APP server 24and a ProSe function 26 via interfaces referred to in FIG. 4 as PC1 andPC3 interfaces, respectively. The ProSe APP server 24 and the ProSefunction 26 may provide server-side functionality related to the D2Dcommunication between the UEs 20. In some embodiments, the communicationfor the PC1 and PC3 interfaces is transported over the E-UTRAN 12 andthe EPC 14 but is transparent to the E-UTRAN 12 and the EPC 14. The EPC14 is connected to the ProSe APP server 24 via a SGi interface andconnected to the ProSe function 26 via a PC4 interface. The ProSe APPserver 24 and the ProSe function 26 are connected via a PC2 interface.Lastly, the ProSe function 26 may use a PC6 interface for communicationbetween internal components of the ProSe function 26.

Systems and methods relating to sharing of non-overlapping time periodsin DRX for different operations (i.e., cellular and D2D operations) areprovided. Before describing embodiments of the present disclosure, adiscussion of DRX is beneficial.

In LTE, DRX has been introduced as one of the key solutions to conservebattery power the wireless device (or UE) 20. DRX is characterized bythe following:

-   -   Per UE mechanism (as opposed to per radio bearer);    -   May be used in RRC_IDLE and RRC_CONNECTED. In RRC_CONNECTED, the        eNB/UE may initiate the DRX mode when there are no        outstanding/new packets to be transmitted/received. In RRC_IDLE        state (aka idle mode), Second Generation (2G) and Third        Generation (3G) terminals use DRX to increase battery life time.        High Speed Packet Access (HSPA) and LTE have introduced DRX also        for RRC connected state.    -   Available DRX cycle values are controlled by the network and        start from non-DRX up to x seconds where x can be 2.56 seconds        in LTE and 5.12 seconds in UTRA.    -   Hybrid Automatic Repeat Request (HARQ) operation related to data        transmission is independent of DRX operation and the UE wakes up        to read the Physical Downlink Control Channel (PDCCH) for        possible retransmissions and/or Acknowledgement/Negative        Acknowledgement (ACK/NAK) signaling regardless of DRX. In the        DL, a timer is used to limit the time the UE stays awake        awaiting for a retransmission;    -   When DRX is configured, the UE may be further configured with an        “on-duration” timer during which time the UE monitors the PDCCHs        for possible allocations;    -   When DRX is configured, periodic Continuous Quality Improvement        (CQI) reports can only be sent by the UE during the        “active-time.” Radio Resource Control (RRC) can further restrict        periodic CQI reports so that they are only sent during the        on-duration;    -   The eNB does not transmit packets to UE during the sleep mode.

RRC_CONNECTED mode DRX should not be confused with DRX in idle mode,which the UE is set into after a prolonged time of air interfaceinactivity. RRC_IDLE mode DRX is also known as paging DRX, i.e. the timethe UE can go to sleep between two paging messages that could contain acommand for the UE to wake up again and change back to RRC_CONNECTEDstate. RRC_IDLE mode DRX is much less fine grained and measured inhundreds of milliseconds or even seconds.

The following definitions apply to DRX in E-UTRAN:

-   -   on-duration: The “on-duration” (sometimes referred to herein as        ON duration or DRX ON duration) is a duration in DL subframes        that the UE waits for, after waking up from DRX, to receive        PDCCHs. If the UE successfully decodes a PDCCH, the UE stays        awake and starts an inactivity timer.    -   inactivity timer: The “inactivity timer” is a duration in DL        subframes that the UE waits to successfully decode a PDCCH, from        the last successful decoding of a PDCCH, failing which it        re-enters DRX (DRX OFF state). The UE shall restart the        inactivity timer following a single successful decoding of a        PDCCH for a first transmission only (i.e., not for        retransmissions).    -   active time: The “active time” is a total duration that the UE        is awake. This includes the on duration of the DRX cycle, the        time the UE is performing continuous reception while the        inactivity timer has not expired, and the time UE is performing        continuous reception while waiting for a DL retransmission after        one HARQ Round Trip Time (RTT). Based on the above, the minimum        active time is of length equal to the on duration, and the        maximum active time is undefined (infinite).        Of the above parameters, the DRX ON duration and the inactivity        timer are of fixed lengths, while the active time is of varying        lengths based on scheduling decision and UE decoding success.        Only on-duration and inactivity timer duration are signaled to        the UE by the eNB.

There is only one DRX configuration applied in the UE 20 at any time.The UE 20 shall apply an ON duration upon wake-up from DRX sleep (i.e.,DRX OFF state).

DRX mode in LTE is illustrated in FIG. 5. DRX is triggered by means ofan inactivity time known as DRX. As can be seen from FIG. 5, the UE 20activity time may be extended if a PDCCH is received during the DRX ONduration. However, it may also be shortened by a Medium Access Control(MAC) DRX command, upon reception of which the UE 20 stops the DRX ONduration timer and DRX inactivity timer. In the particular exampleillustrated in FIG. 5, the UE 20 is initially awake (i.e., in DRX ONstate). Before the DRX ON duration has expired, the UE 20 successfullydecodes a PDCCH and, in response, starts the inactivity timer. Beforethe inactivity timer has expired, the UE 20 successfully decodes anotherPDCCH and, in response, resets the inactivity timer. This time, theinactivity timer expires before any new PDCCH is successfully decoded bythe UE 20. As such, the UE 20 enters DRX. In particular, when theinactivity timer is not running, the UE 20 begins a DRX cycle byremaining in the DRX ON state for the DRX ON duration. When no PDCCH issuccessfully decoded by the UE 20 during the DRX ON duration, the UE 20transitions to the DRX OFF state, where the UE 20 is asleep. The UE 20remains in the DRX OFF state until the next DRX cycle begins.

Embodiments disclosed herein are directed to:

-   -   Embodiments of the UE 20 and methods of operation thereof for        sharing time between different operation types in DRX;    -   Embodiments of a network node (e.g., the base station or eNB 16        or some other network node) and methods of operation thereof for        adapting DRX to enable DL cellular and/or D2D operations;    -   Embodiments of a network node (e.g., the base station or eNB 16        or some other network node) and methods of operation thereof to        enable DL cellular and/or D2D operations; and    -   Embodiments of the UE 20 and methods of operation thereof for        signaling capability related to sharing time between different        operation types on DRX.

As an exemplary advantage to embodiments described herein, a D2D capableUE (e.g., the UE 20) that cannot receive D2D and cellular signals at thesame time is configured by a network node (e.g., the eNB 16) with a DRXcycle(s) for enabling the UE to perform D2D and cellular operationsduring non-overlapping times during the DRX cycle(s). The UE may furtherbe configured with one of the time sharing mechanisms or rules forperforming both D2D and cellular operations during non-overlapping timesduring the DRX cycle(s).

According to some embodiments, a method is disclosed comprisingobtaining a rule (e.g., autonomous selection, predefined or configuredby a network node) to be used by the UE 20 to perform D2D and cellularoperations over non-overlapping times of a DRX cycle, which DRX cycle isconfigured or being configured at the UE 20; determining a first timeperiod and a second time period within a DRX cycle, wherein said firstand second time periods do not overlap in time, and said first andsecond time periods are used for D2D operation and cellular operationrespectively; and performing D2D operation and cellular operation duringthe determined first and second time periods respectively.

Other embodiments are directed to a method performed in a network nodeserving a D2D capable UE (e.g., the UE 20), comprising determining basedon one or more criteria a rule to be used by the UE for performing D2Dand cellular operations over non-overlapping times of a DRX cycleconfigured or being configured at the UE; configuring the UE with thedetermined rule, said rule enabling the UE to determine a first timeperiod and a second time period within a DRX cycle, wherein said firstand second time periods do not overlap in time, and said first andsecond time periods are used for D2D operation and cellular operationrespectively; and, according to one exemplary embodiment, adapting basedon one or more criteria the DRX cycle configuration to enable the UE toperform D2D and cellular operations over non-overlapping times.

It is noted that the “first” and the “second” non-overlapping times donot have to imply any specific order, according to various embodiments.One of ordinary skill in the art will realize that various communicationnodes (e.g., a UE or any other station) could perform the processesdescribed herein.

Embodiments of a UE and Methods of Operation Thereof for Sharing TimeBetween Different Operation Types in DRX

As discussed above, embodiments of a method of operation of the UE 20,which is a D2D capable UE or D2D UE, to share time between differentoperation types (e.g., cellular and D2D operations) in DRX aredisclosed. In these embodiments, the UE 20 is assumed to be configuredby a network node (e.g., the base station or eNB 16 or some othernetwork node) with at least one DRX cycle for D2D operation, at leastone DRX cycle (another DRX cycle) for DL cellular operation, or the same(common) at least one DRX cycle for both D2D and DL cellular operations.The UE 20 configured with a DRX cycle(s) receives a radio signal duringthe ON duration of the DRX cycle(s). The UE 20 splits time during theDRX cycle(s) for D2D operation and cellular operation such that the D2Dand cellular operations do not occur at the same time. The D2D operation(transmit and/or receive) may be scheduled in one or more of thefollowing ways: configured by UE 20 autonomously (e.g., at least somescheduling-related parameters are decided by the UE 20), configured byanother UE 20, or configured by a network node (e.g., the eNB 16). A D2Dconfiguration may explicitly indicate resources (e.g., subframes,Resource Blocks (RBs), symbols, time slots, etc.) allocated for a D2Doperation. Thus, in the description below, adapting D2D operation mayalso imply adapting the D2D configuration in some embodiments.

The splitting of time during DRX between D2D and cellular operations isgoverned according to any one or more of the following exemplary rulesor principles.

Exemplary Rule #1—Using ON and OFF Durations: In some exemplaryembodiments or implementations, the UE 20 receives only one of the twotypes of signals (DL cellular or D2D) at a time during the ON durationof a configured DRX cycle, and receives the other type of signal duringthe OFF period of the same DRX cycle (i.e., outside the ON duration)provided that the other type of signal is available during the OFFduration. For example, the UE 20 may receive cellular signals and D2Dsignals during the ON duration and OFF duration of the DRX cycle (e.g.,receive cellular signals during the ON duration and receive D2D signalsduring the OFF duration, or vice versa).

One example of exemplary rule #1 is illustrated in FIG. 6. FIG. 6illustrates multiple consecutive DRX ON durations and OFF durations.Each DRX ON duration and the corresponding DRX OFF duration form a DRXcycle. The consecutive DRX cycles may be referred to herein as a DRXpattern, which includes multiple consecutive DRX cycles each having acorresponding DRX ON duration and a DRX OFF duration. In this example,the UE 20 performs cellular operation(s) (e.g., reception of cellularsignals) during the DRX ON duration and performs D2D operation(s) (e.g.,reception of D2D signals) during the DRX OFF duration.

Exemplary rule #1 is further elaborated with a few examples. In a firstexample, the UE 20 is configured with a DRX cycle for only DL cellularoperation. As an example, the DRX cycle is 640 milliseconds (ms) with anON duration of 20 ms. The UE 20 therefore receives DL cellular signalsduring the ON duration of the configured DRX cycle. In existingsolutions, the UE 20 can receive the D2D signals at any time includingduring the ON duration of the DRX cycle. However, according to thisembodiment, the UE 20 receives only DL cellular signals during the ONduration, but the UE 20 receives the D2D signals during the OFF durationof the DRX cycle. Typically, D2D signals (e.g., synchronization signals,beacon signals, discovery signals, etc.) are transmitted periodically.

In a second example, the UE 20 is configured with a common DRX cycle forboth DL cellular operation and D2D operation. As an example, the DRXcycle is also 640 ms with an ON duration of 20 ms. The UE 20, based onautonomous decision, decides to receive only DL cellular signals duringthe ON duration of the configured DRX cycle. In existing solutions, theUE 20 will not be able to receive the D2D signals during the same ONduration where the DL cellular signal is received and, therefore, no D2Dsignal reception will take place. However, according to this embodiment,the UE 20 will also attempt to receive the D2D signals during the OFFduration of the DRX cycle. If the D2D signals are available, then the UE20 receives them. In this way, the performances of both DL cellular andD2D operations are enhanced.

Exemplary Rule #2—Sharing Different ON Durations: In some otherexemplary embodiments or implementations, the UE 20 may receive bothtypes of signals, but in different ON durations (e.g., DL cellularduring the ON duration of one DRX cycle and D2D signals during the ONduration of the next DRX cycle and so on). In another example, the UE 20may receive cellular signals in three out of four consecutive ONdurations of corresponding consecutive DRX cycle whereas the UE 20 mayreceive D2D signals in the remaining one out of four consecutive ONdurations of the corresponding consecutive DRX cycles.

One example of exemplary rule #2 is illustrated in FIG. 7. This exampleis further explained as follows. Assume that the UE 20 is alsoconfigured with a common DRX cycle for both DL cellular operation andD2D operation. The DRX cycle is the same as in previous examples. The UE20, based on an indication received from a network node, decides toreceive DL cellular signals during three out of any four consecutive DRXON durations and D2D signals during the remaining one out of four DRX ONdurations. The UE 20 may also be informed about the three consecutiveDRX ON durations for receiving DL cellular and/or the DRX ON durationfor receiving the D2D signals. The UE 20 may also determine the DRX ONduration to be used for DL cellular or D2D based on a predefined rule,e.g., initially three DRX ON durations after receiving the indicationfrom the network node. The UE 20 therefore receives DL cellular and D2Dsignals during different DRX ON durations. In this way, the UE 20 isable to receive both types of signals. In existing solutions, the UE 20will miss one of the two types of signals in this scenario comprising ofcommon DRX cycles. In order to compensate for an inability to schedulethe DL cellular signals in certain ON durations, for example the networknode may assign more resources (e.g., more RBs, larger data block size,etc.) to the UE 20 during the ON durations used for DL cellular signals.In this way, the UE 20 throughput can be maintained and performancedegradation can be avoided.

Exemplary Rule #3—Sharing the same ON duration: In some embodiments orimplementations, the UE 20 may receive both types of signals during thesame ON duration but during non-overlapping times (e.g., receive DLcellular signals during an initial 70% of the ON duration and receiveD2D signals during the remaining 30% of the same ON duration). Thisexample is illustrated in FIG. 8. Such a decision may be made by the UE20 autonomously or be network controlled, e.g., a network node may allowor not allow such sharing or, if it is allowed, the network node mayalso control the sequence and/or the amount of sharing (e.g., cellularfirst and then D2D; 50% for cellular and 50% for D2D, or 70% forcellular and 30% for D2D, etc.).

In one example, in case the sharing is not allowed or the time availablefor cellular DL (out of the 20 ms in this example) is above a threshold,the existing cellular requirements can apply. But if sharing is allowedby the network node or the time left for cellular DL during the DRX ONis below a threshold, either some adaptation in the UE 20 may be neededto ensure that the current cellular requirements are still met (sincefewer subframes are now available for DL cellular) or a second set ofrequirements which are more relaxed compared to the case with no sharingapplies for the DL cellular.

Exemplary Rule #4—Ensuring a certain minimum time (Tmin) and/or maximumtime (Tmax) between the first and the second non-overlapping timeperiods: In some embodiments, the first and the second non-overlappingtimes are configured such that they are separated in time by a time (t)for which one or both of the following conditions hold:Tmin≦t, andt≦Tmax.

In one example, the separation may be determined by a relation betweenD2D operation and DL cellular operation, e.g., the UE 20 receives someassistance or configuration for D2D operation via a cellular DL controlchannel (e.g., such as PDCCH or Enhanced or Evolved Physical DownlinkControl Channel (EPDCCH)) or via DL higher-layer protocol (e.g., RRC)and thus the UE 20 may need some time to receive and process thereceived information (e.g., Tmin=4 ms).

In another example, the UE 20 may need to perform a D2D operation afterno more Tmax after a cellular operation (e.g., receiving some D2Drelated data from the network), or vice versa, the UE 20 may need totrigger some cellular operation within Tmin after a D2D operation.

In yet another example, the minimum time spacing (Tmin) may be neededfor receiver switching due to Radio Frequency (RF) aspects.

In yet another example, there may be Tmin1 needed due to a first reason(reason 1) and Tmin2 needed due to a second reason (reason 2), thus theresulting Tmin can be determined, e.g., as:Tmin=max(Tmin1,Tmin2).

In some embodiments, e.g. when the two reasons are associated withdifferent D2D operations, the UE 20 may apply an additional conditionthat abs(Tmin2−Tmin1)<threshold (otherwise the two D2D operations may beperformed in non-contiguous times, e.g., the first D2D operation duringa first DRX OFF duration and the second D2D operation during a secondDRX OFF duration).

Similarly, there may be Tmax1 needed due to a first reason (reason 1)and Tmax2 needed due to a second reason (reason 2), thus the resultingTmax can be determined, e.g., as:Tmax=min(Tmax1,Tmax2).

In some embodiments, e.g. when the two reasons are associated withdifferent D2D operations, the UE 20 may apply an additional conditionthat abs(Tmax2−Tmax1)<threshold (otherwise the two D2D operations may beperformed in non-contiguous times, e.g., the first D2D operation duringa first DRX OFF duration and the second D2D operation during a secondDRX OFF duration).

Exemplary Rule #5—Ensuring a certain order between the first and thesecond non-overlapping times: In some embodiments, the first and thesecond non-overlapping times are configured in a certain order, e.g.,the first non-overlapping time (for D2D operation) appears first in timefollowed by the second non-overlapping time (for cellular DL operation).In yet another example, the order may be the opposite, e.g., the secondnon-overlapping time appears in time before the first non-overlappingtime.

In one example, the order may be determined, e.g., by a relation betweenthe D2D operation and the cellular operation of the UE 20. For example,the UE 20 may need to receive a D2D configuration via cellular DL (e.g.,RRC or PDCCH/EPDCCH) before it can perform the D2D operation based onthat configuration.

Exemplary Rule #6—Combined Mechanism: In yet another example, the UE 20may receive the types of signals by combining any two or more of theembodiments and examples described with respect to exemplary rules #1through #5.

In the above examples, the UE 20 detects the DRX cycle configuration anddeliberately adapts its radio receiver to be able to receive the twotypes of signals at non-overlapping times regardless of whether DRX isconfigured for receiving only one or both types of signals.

In some embodiments, any one of the above rules to be used by the UE 20for splitting of time between D2D and DL cellular operations is decidedby the UE 20 based on one or more of the following principles:

-   -   The UE 20 itself (autonomously) decides which rule(s) to use        based on, e.g., UE battery life. If the UE battery life is above        a threshold, then the UE 20 may choose exemplary rule #1 and        operate D2D during the OFF duration. As another example, the        criterion used by the UE 20 to decide which rule(s) to apply is        the availability of D2D signals. If D2D signals are available        during the ON duration only, then the UE 20 may use exemplary        rule #2 or exemplary rule #3.    -   The rule(s) to use may be predefined. For example, in case there        is only one specified rule in the standard, the UE 20 will use        that rule. Yet another example of a predefined rule is that UE        20 uses a certain rule(s) depending on the DRX cycle length        and/or ON duration of the DRX cycle. For example, if the DRX ON        duration is above a threshold (e.g., more than 10 ms), only then        does the UE 20 use exemplary rule #3.In yet another example of a        predefined rule, the UE 20 may choose a rule depending upon the        DRX cycle length, e.g., the UE 20 uses exemplary rule #1 in case        the DRX cycle is larger than a threshold (e.g., 640 ms). A        certain one or more rules may also apply when certain conditions        are met and/or in certain scenarios and/or may be triggered by        some events.    -   The rule(s) used by the UE 20 may be configured by a network        node.    -   Any combination of the above. For example, a predefined rule        applies always when a certain condition is met, but at least one        parameter (e.g., a threshold) in that rule is configured by a        network node or selected autonomously by the UE 20.

In case of autonomous decision by the UE 20 for selecting a rule(s) forDRX sharing, the UE 20 may also inform a network node and/or another UE20 about the rule which is being or expected to be used by the UE 20.The UE 20 may also request a network node to provide the UE 20 with thevalues of one or more parameters related to the rule selected by the UE20.

Even in case of autonomous decision or based on a predefined rule, oneor more parameters to enable the sharing of time during the DRX cyclebetween D2D and DL cellular operations may still be configured at the UE20 by a network node. Alternatively, the parameter values may bepredefined or autonomously decided by the UE 20 itself. For example, thenetwork node may indicate which one of the methods described herein(e.g., which one of exemplary rule #1 through exemplary rule #6) thatthe UE 20 may use for sharing the time between D2D and cellularoperations. The network node may also indicate for example the amount oftime within an ON duration to be split by the UE 20 between D2D andcellular operations in case of exemplary rule #3 described above.

FIG. 9 is a flow chart that illustrates the operation of the UE 20according to the embodiments described above. Note that while thisprocess is described as being performed by the UE 20, this process mayalternatively be performed by another node or processing unitcommunicatively coupled to the UE 20. As illustrated, optionally (i.e.,in some embodiments), the UE 20 obtains one or more DRX cycle sharingrules/configurations (step 100). As discussed above, in someembodiments, the UE 20 determines the DRX sharing rule(s) autonomously.In other embodiments, the UE 20 receives an indication of the DRXsharing rule(s) from a network node. In yet another embodiment, the UE20 obtains the DRX sharing rules via a combination of autonomousdecision by the UE 20 and information received from a network node(e.g., determine which DRX sharing rule to apply autonomously butreceive threshold or parameter values from the network node). Asdiscussed above, the DRX sharing rule(s) may include: sharing using DRXON and DRX OFF durations (i.e., exemplary rule #1), sharing differentDRX ON durations (i.e., exemplary rule #2), sharing the same DRX ONduration (i.e., exemplary rule #3), ensuring Tmin and/or Tmax betweennon-overlapping time periods within a DRX cycle(s) used for D2D andcellular operations (i.e., exemplary rule #4), ensuring a certain orderbetween D2D and cellular operations (i.e., exemplary rule #5), or anycombination thereof (i.e., exemplary rule #6).

The UE 20 determines non-overlapping time periods within one or more DRXcycles for performing D2D and cellular operations, e.g., according tothe obtained DRX cycle sharing rule(s) (step 102). For instance, the UE20 determines a first time period within a DRX cycle for cellularoperation(s) and a second time period within the same DRX cycle or adifferent DRX cycle (depending on the embodiment or DRX sharing rule)for D2D operation(s). The first and second time periods arenon-overlapping such that the UE 20 is able to, e.g., receive bothcellular signals and D2D signals even if/though the UE 20 is onlycapable of receiving one of these types of signals at a time.

The UE 20 then performs D2D operation(s) and cellular operation(s)during the determined non-overlapping time periods within the DRXcycle(s) (step 104). While not limited thereto, in some embodiments, theD2D operation(s) include reception of D2D signals, and the cellularoperation(s) include reception of DL cellular signals.

Embodiments of a Network Node and Methods of Operation Thereof forAdapting DRX to Enable DL Cellular and/or D2D Operations

In some embodiments, a network node (e.g., the eNB 16 or some othernetwork node) serving a D2D capable UE 20, which is or is beingconfigured with at least one DRX cycle, configures the UE 20 with one ormore rules or one or more parameters associated with said rules to beused by the UE 20 for sharing the time between D2D and cellularoperations during the DRX cycle. Some examples of such rules ormechanisms and their associated parameters are described below. Thenetwork node may configure the UE 20 only with one or more parameters ofthe rule(s) in case the UE 20 is already configured with the rule or theUE 20 uses the rule based on a predefined principle.

The network node may use one or more criteria to decide which ruleshould be used by the UE 20 for splitting the time of the DRX cycle forcellular and D2D operations. Examples of such criteria are:

-   -   UE D2D capability(-ies): For example, the criteria may include        whether the UE 20 supports certain D2D operations in certain        scenarios and/or under certain conditions.    -   Amount of cellular traffic such as buffer size of cellular        and/or D2D: For example, if the size of a UE buffer (containing        cellular traffic) for the UE 20 is larger than a threshold, then        the network node may configure the UE 20 to use exemplary rule        #1 (described above) so that the entire ON duration can be used        for cellular operation.    -   UE battery life and/or power consumption: If UE battery life        status of the UE 20 is below a threshold and/or expected power        consumption by the UE 20 due to cellular and/or D2D operations        is above a threshold, then the network node may use exemplary        rule #2 or exemplary rule #3 (described above). This is to save        UE battery life.    -   DRX cycle length: If DRX cycle length is above a threshold, then        the network node may configure the UE 20 to use exemplary rule        #1 (described above).    -   Length of ON duration of DRX cycle: If the DRX cycle length is        above a threshold, then the network node may configure the UE 20        to use exemplary rule #3 only if the DRX ON duration is        sufficiently larger, i.e. above a threshold, e.g., at least 20        ms.    -   Occasions of D2D operation: The network node may also take into        account the occasions of D2D operation when selecting a rule.        For example, if D2D signals can be received by the UE 20 during        the OFF duration of the DRX cycle, then the network node may        configure the UE 20 with exemplary rule #1.    -   UE radio receiver capability: For example, the network node may        select any of the rules if the UE 20 has only one radio receiver        or limited receiver capability (e.g., limited amount of        processors and/or memory units, etc.) to receive only one of the        two types of signals (D2D or cellular signals) at the same time.        Otherwise, the network node may not select any of the rules        since the UE 20 can receive both types of signals in the ON        duration at the same time.    -   Relation between D2D operation and DL cellular operation for the        UE: For example, the network node may consider whether the UE 20        is expected to receive some assistance data or a D2D        configuration via a cellular link in order to perform the D2D        operation.    -   UE state: For example, the network node may consider whether the        UE 20 is in RRC_IDLE or RRC_CONNECTED, since the UE operation        may be more restricted (in supported/allowed operation and also        UE 20 configuration).

After the rule(s) for DRX sharing has been selected by the network node,the UE 20 is configured with the selected rule(s) and may further beconfigured with one or more parameters associated with the selectedrule(s).

FIG. 10 is a flow chart that illustrates the operation of a network nodeaccording to at least some of the embodiments described above. Asdiscussed above, the network node determines one or more DRX cyclesharing rules/configurations to be used by the UE 20 (step 200). Asdiscussed above, the network node can use various criteria for thisdetermination, depending on the particular embodiment or implementation.In particular, when determining the DRX cycle sharing rule(s) (sometimesreferred to herein simply as rules or DRX sharing rules), the networknode may consider one or more of the following: D2D capability(-ies) ofthe UE 20, amount of cellular traffic for the UE 20, battery life and/or(expected) power consumption of the UE 20, DRX cycle length, length ofDRX ON duration, occasions of D2D operation, radio receivercapability(-ies) of the UE 20, relationship between D2D operation and DLcellular operation, and UE state of the UE 20, as described above.

The network node configures the UE 20 with the determined DRX cyclesharing rule(s) (step 202). This configuration may be performed usingany suitable signaling (e.g., RRC signaling). Further, thisconfiguration may include both the configuration of the DRX cyclesharing rule(s) and the configuration of any parameters utilized by theDRX cycle sharing rule(s). As discussed above, the DRX cycle sharingrule(s) enable the UE 20 to determine non-overlapping type periodswithin one or more DRX cycles during which to perform different types ofoperations (e.g., cellular and D2D operations).

Optionally, in some embodiments, the network node adapts the DRX cyclesharing rule(s) for the UE 20 and/or DRX cycle configuration (step 204).In some embodiments, the DRX cycle sharing rule(s) are adapted based onany suitable criteria such as, for example, any combination of one ormore of the criteria discussed above with respect to step 200.Adaptation of the DRX cycle sharing rule(s) enables, e.g., dynamicadjustment of the DRX cycle sharing rule(s) in response to changingconditions. In some embodiments, in addition to or as an alternative toadapting the DRX sharing rule(s), the network node adapts the DRX cycleto enable the UE 20 to perform D2D and cellular operations overnon-overlapping time periods. This type of adaptation is discussed belowin more detail. However, in general, the DRX cycle may be adapted byadapting the DRX ON duration, adapting the DRX cycle based on occasionsof D2D operations, and/or adapting the DRX cycle to satisfy Tmin and/orTmax.

Embodiments of a Network Node and Methods of Operation Thereof to EnableDL Cellular and/or D2D Operations

In some embodiments, the UE 20 is assumed to be configured or beingconfigured by the network node with at least one DRX cycle for D2Doperation and/or for cellular operation. The UE 20 is expected to sharethe time during the DRX cycle(s) between D2D and cellular operations,e.g., due to limited radio receiver capability. The network node mayalso deliberately configure the UE 20 with at least one DRX cycle toenable the UE 20 to share time between D2D and cellular operations, incase the UE 20 cannot receive D2D and cellular signals at the same time.

The network node adapts the DRX configuration in order to facilitate theUE 20 to more effectively and efficiently share its radio receiverresource between D2D and cellular operations when operating in DRX. Insome embodiments, a method of operation of a network node comprises thefollowing steps, as illustrated in FIG. 11. The network node determinesthat the UE 20 is configured or being configured in DRX for receiving atleast one of the D2D and cellular signals (step 300). The network nodedetermines that the UE 20 is sharing or expected to share time duringDRX for D2D operation and/or for cellular operation (step 302). Forexample, the network node may determine this based on UE radio receivercapability or an indication from the UE 20 that the UE 20 can onlyreceive one of the two types of signals. The network node may alsodetermine based on historical data or previous operation of the UE 20that the UE 20 cannot receive both types of signals at the same time.

The network node adapts an existing DRX cycle configuration orconfigures a DRX cycle for the UE 20 based on one or more criteria toenable the UE 20 to share the time during the DRX between D2D andcellular operations (step 304). Examples of this adaptation include, butare not limited to:

-   -   Type of rule to be used: For example, in case the network node        decides to use exemplary rule #3 (described above), then the        network node may adapt (e.g., increase) the length of the ON        duration.    -   Occasions of D2D operations: For example, the network node may        determine the occasions when the UE 20 is expected to receive        D2D signals. The network node may determine the D2D signal        occasions based on one or more of: predefined information,        indication received from another network node, or from the UE        20. The network node then configures the UE 20 with a DRX cycle        or adapts DRX cycle parameter(s) so that the UE 20 can receive        D2D signals. For example, in case of exemplary rule #1        (described above), the network node may extend or shift the        start of the DRX cycle length in case the D2D signals partly or        fully overlap with the current DRX cycle.    -   The DRX configuration parameters may also be adapted to Tmin and        Tmax in exemplary rule #4 (described above) and/or the order of        the D2D and cellular operations, if related, by exemplary rule        #5 (described above), e.g., in case of jointly applying        exemplary rule #3 and exemplary rule #4 the DRX ON period may be        extended to adapt to Tmin.

Embodiments of a UE and Methods of Operation Thereof for SignalingCapability Related to Sharing Time Between Different Operation Types onDRX

According to some embodiments, the UE 20 signals a capability to anetwork node or a second UE 20 indicating whether it is capable ofsharing time of a DRX cycle(s) between D2D operation(s) and cellularoperation(s) such that the UE 20 does not receive D2D and cellularsignals during the same time. The UE capability information signaled tothe network node or a second UE 20 may also indicate which one or moreof the rules or principles (e.g., which of exemplary rules #1 through #6described above) can be used by the UE 20 for sharing the time of theDRX cycle(s) between D2D operation and cellular operation. Thecapability may also apply for certain carrier frequencies/frequencybands and/or their combinations.

The UE 20 may signal the capability information to the network nodeautonomously, based on an explicit request received from the networknode, triggered by an event or condition, together with othercapabilities at joining a cell, or when indicating D2D-relatedcapabilities to the network. The network node (e.g., an eNB or a corenetwork node) or a second UE 20 may use the received UE capabilityinformation for one or more of the following purposes:

-   -   Transmit the capability information to another network node,        e.g. any of: the eNB or the second UE 20 sends it to another        eNB, the eNB or the second UE 20 sends it to a Core Network (CN)        node (e.g., a MME or a ProSe server), the CN node sends it to        the eNB, the eNB sends it to a third UE 20 (see, e.g., FIG. 2),        etc.    -   Store the capability information in memory and retrieve it at a        future time for use.    -   Decide, based on the capability information, which of the        criteria or principles for sharing the time in DRX is to be        employed for the UE 20.    -   Adapt cellular and/or D2D scheduling for the UE 20.    -   Adapt the D2D-related data and configuration broadcasted by the        network.

FIG. 12 illustrates the operation of the UE 20 to send capabilityinformation to a node according to some embodiments of the presentdisclosure. As illustrated, the UE 20 sends, or transmits, capabilityinformation related to sharing time between different operation types onDRX to another node 28 (step 400). This other node 28 may be a networknode (e.g., the eNB 16) or another UE 20. The node 28 then utilizes thecapability information and/or sends the capability information toanother node (step 402). For example, as discussed above, in someembodiments the node 28 is a network node, and the network node utilizesthe capability information to determine and/or adapt DRX sharing rule(s)and/or associated parameters for the UE 20. In other embodiments, thenode 28 is another UE 20, and the node 28 sends the capabilityinformation to another node, e.g., a network node.

FIG. 13 is a block diagram of the UE 20, according to one exemplaryembodiment, that can be used in one or more of the non-limiting exampleembodiments described herein. The UE 20 may in some embodiments be amobile device that is configured for Machine-to-Machine (M2M) orMachine-Type Communication (MTC). The UE 20 comprises a processingmodule 30 that controls the operation of the UE 20. As will beappreciated by one of skill in the art, the processing module 30includes one or more processors, or processor circuits, such as, forexample, one or more microprocessors or Central Processing Units (CPUs),one or more Application Specific Integrated Circuits (ASICs), one ormore Field Programmable Gate Arrays (FPGAs), or one or more other typesprocessing circuits. The processing module 30 is connected to a receiveror transceiver module 32 with associated antenna(s) 34 which are used toreceive signals from or both transmit signals to and receive signalsfrom the base station 16 and other D2D capable UEs 20. To make use ofDRX, the processing module 30 can be configured to deactivate thereceiver or transceiver module 32 for specified lengths of time. The UE20 also comprises a memory module 36 that is connected to the processingmodule 30 and that stores program and other information and datarequired for the operation of the UE 20. In some embodiments, the UE 20may optionally comprise a satellite positioning system (e.g., GPS)receiver module (not shown) that can be used to determine the positionand speed of movement of the UE 20.

In some embodiments, a computer program including instructions which,when executed by at least one processor, causes the at least oneprocessor to carry out the functionality of the UE 20 according to anyof the embodiments described herein is provided. In some embodiments, acarrier containing the aforementioned computer program product isprovided. The carrier is one of an electronic signal, an optical signal,a radio signal, or a computer readable storage medium (e.g., anon-transitory computer readable medium such as memory).

FIG. 14 is a block diagram of the UE 20 according to some otherembodiments of the present disclosure. In this example, the UE 20includes a DRX sharing rule obtaining module 38 (optional), a DRX timeperiod determination module 40, and a performance module 42, each ofwhich is, in this embodiment, implemented in software. The DRX sharingrule obtaining module 38 operates to obtain one or more DRX sharingrule(s) as described above. The DRX time period determination module 40operates to determine the non-overlapping time periods for the differenttypes of operations (e.g., cellular and D2D operations) e.g., based onthe DRX sharing rule(s). The performance module 42 performs thedifferent types of operations in the non-overlapping time periods, asdescribed above.

FIG. 15 shows the base station 16 (for example a Node B or an eNB) thatcan be used in example embodiments described herein. It will beappreciated that other types of network nodes will include similarcomponents. It will also be appreciated that although a macro eNB willnot in practice be identical in size and structure to a micro eNB, forthe purposes of illustration, the base stations 16 are assumed toinclude similar components. Thus, the base station 16 comprises aprocessing module 44 that controls the operation of the base station 16.As will be appreciated by one of skill in the art, the processing module44 includes one or more processors, or processor circuits, such as, forexample, one or more microprocessors or CPUs, one or more ASICs, one ormore FPGAs, or one or more other types processing circuits. Theprocessing module 44 is connected to a transceiver module 46 withassociated antenna(s) 48 which are used to transmit signals to, andreceive signals from, UEs 20 in the cellular communications network 10.The base station 16 also comprises a memory module 50 that is connectedto the processing module 44 and that stores program and otherinformation and data required for the operation of the base station 16.The base station 16 also includes components and/or circuitry 52 forallowing the base station 16 to exchange information with other basestations 16 (for example via an X2 interface) and components and/orcircuitry 54 for allowing the base station 16 to exchange informationwith nodes in the core network 14 (for example via the S1 interface). Itwill be appreciated that base stations for use in other types ofnetworks (e.g., Universal Terrestrial Radio Access Network (UTRAN) orWCDMA RAN) will include similar components to those shown in FIG. 15 andappropriate interface circuitry 52, 54 for enabling communications withthe other network nodes in those types of networks (e.g., other basestations, mobility management nodes, and/or nodes in the core network14).

In some embodiments, a computer program including instructions which,when executed by at least one processor, causes the at least oneprocessor to carry out the functionality of the base station 16 (orother network node) according to any of the embodiments described hereinis provided. In some embodiments, a carrier containing theaforementioned computer program product is provided. The carrier is oneof an electronic signal, an optical signal, a radio signal, or acomputer readable storage medium (e.g., a non-transitory computerreadable medium such as memory).

FIG. 16 is a block diagram of the base station 16 according to someother embodiments of the present disclosure. In this example, the basestation 16 includes a DRX sharing rule determination module 56, a DRXsharing configuration module 58, and an adaptation module 60 (optional),each of which is, in this embodiment, implemented in software. The DRXsharing rule determination module 56 operates to determine one or moreDRX sharing rule(s) to be used by the UE 20, as described above. The DRXsharing configuration module 58 operates to configure the UE 20 with thedetermined DRX sharing rule(s), as described above. The adaptationmodule 60 operates to, in some embodiments, adapt the DRX sharingrule(s) and/or the DRX configuration of the UE 20, as also describedabove.

As described herein, some exemplary, but non-limiting embodiments of thepresent disclosure are as follows. In some embodiments, a methodcomprises obtaining a rule to be used by a UE for performing D2D andcellular operations over non-overlapping times of a DRX cycle configuredor being configured at the UE, determining a first time period and asecond time period within a DRX cycle(s), wherein said first and secondtime periods do not overlap in time, and said first and second timeperiods are used for D2D operation and cellular operation respectively;and performing D2D operation and cellular operation during thedetermined first and the second time periods respectively. In someembodiments, this method is performed by the UE.

In some embodiments, a UE comprises a processing unit configured toperform the steps of: obtaining a rule to be used by the UE forperforming D2D and cellular operations over non-overlapping times of aDRX cycle(s) configured or being configured at the UE; determining afirst time period and a second time period within a DRX cycle(s),wherein said first and second time periods do not overlap in time, andsaid first and second time periods are used for D2D operation andcellular operation respectively; and performing D2D operation andcellular operation during the determined first and second time periodsrespectively.

In some embodiments, a method performed in a network node serving a D2Dcapable UE comprises determining, based on one or more criteria, a ruleto be used by the UE for performing D2D and cellular operations overnon-overlapping times of a DRX cycle(s) configured or being configuredat the UE; and configuring the UE with the determined rule, wherein saidrule enables the UE to determine a first time period and a second timeperiod within a DRX cycle(s), and wherein said first and second timeperiods do not overlap in time, and said first and second time periodsare used for D2D operation and cellular operation respectively. In someembodiments, this method further comprises adapting, based on one ormore criteria, the DRX cycle configuration to enable the UE to performD2D and cellular operations over non-overlapping times.

In some embodiments, a base station comprises a processing unitconfigured to perform the steps of: determining, based on one or morecriteria, a rule to be used by the UE for performing D2D and cellularoperations over non-overlapping times of a DRX cycle(s) configured orbeing configured at the UE; and configuring the UE with the determinedrule, wherein said rule enables the UE to determine a first time periodand a second time period within a DRX cycle, and wherein said first andsecond time periods do not overlap in time, and said first and secondtime periods are used for D2D operation and cellular operationrespectively. In some embodiments, the processing unit is furtherconfigured to perform the step of adapting, based on one or morecriteria, the DRX cycle configuration to enable the UE to perform D2Dand cellular operations over non-overlapping times.

As a result of the foregoing methods and systems, a UE can be enabled todynamically share its receiver between cellular and D2D operationswithout degrading the performance of any of the two operations below adesired level. There is an overall performance benefit of cellular aswell as D2D operations by exploiting DRX configuration without losingdata. Further, the network can adapt DRX configuration to enable the UEto receive D2D or cellular signals, whichever is considered morecritical at a given time or for given application.

While processes in the figures may show a particular order of operationsperformed by certain embodiments of the disclosure, it should beunderstood that such order is exemplary (e.g., alternative embodimentsmay perform the operations in a different order, combine certainoperations, overlap certain operations, etc.).

While the disclosure has been described in terms of several embodiments,those skilled in the art will recognize that the disclosure is notlimited to the embodiments described and can be practiced withmodification and alteration within the spirit and scope of the appendedclaims. The description is thus to be regarded as illustrative insteadof limiting.

The following acronyms are used throughout this disclosure.

-   -   2G Second Generation    -   3G Third Generation    -   3GPP 3^(rd) Generation Partnership Project    -   ACK Acknowledgement    -   APP Application    -   ASIC Application Specific Integrated Circuit    -   CDMA Code Division Multiple Access    -   CN Core Network    -   CPU Central Processing Unit    -   CQI Continuous Quality Improvement    -   D2D Device-to-Device    -   DL Downlink    -   DRX Discontinuous Reception    -   eNB Enhanced or Evolved Node B    -   EPC Enhanced or Evolved Packet Core    -   EPDCCH Enhanced or Evolved Physical Downlink Control Channel    -   E-UTRAN Enhanced or Evolved Universal Terrestrial Radio Access        Network    -   FDD Frequency Division Duplexing    -   FPGA Field Programmable Gate Array    -   GPS Global Positioning System    -   GSM Global System for Mobile Communications    -   HARQ Hybrid Automatic Repeat Request    -   HD-FDD Half Duplex Frequency Division Duplexing    -   HSPA High Speed Packet Access    -   IP Internet Protocol    -   LTE Long Term Evolution    -   M2M Machine-to-Machine    -   MAC Medium Access Control    -   MME Mobility Management Entity    -   ms Millisecond    -   MTC Machine-Type Communication    -   NACK Negative Acknowledgement    -   O&M Operations and Maintenance    -   P2P Peer-to-Peer    -   PDA Personal Digital Assistant    -   PDCCH Physical Downlink Control Channel    -   PGW Packet, or Packet Data Network, Gateway    -   PLMN Public Land Mobile Network    -   ProSe Proximity Service    -   QoS Quality of Service    -   RAN Radio Access Network    -   RAT Radio Access Technology    -   RB Resource Block    -   RF Radio Frequency    -   RLC Radio Link Control    -   RNC Radio Network Controller    -   RRC Radio Resource Control    -   RRH Remote Radio Head    -   RRM Radio Resource Management    -   RTT Round Trip Time    -   SA Scheduling Assignment    -   SGW Serving Gateway    -   SON Self-Organizing Network    -   TDD Time Division Duplexing    -   UE User Equipment    -   UL Uplink    -   UTRA Universal Terrestrial Radio Access    -   UTRAN Universal Terrestrial Radio Access Network    -   VoIP Voice over Internet Protocol    -   VPN Virtual Private Network    -   WCDMA Wideband Code Division Multiple Access    -   WLAN Wireless Local Area Network

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present disclosure. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

What is claimed is:
 1. A wireless device enabled to operate in acellular communications network, comprising: a transceiver modulecomprising a receiver; a processing module comprising one or moreprocessing circuits; and a memory module storing instructions executableby the processing module whereby the wireless device is operable to:determine a first time period within a Discontinuous Reception, DRX,cycle for cellular operation and a second time period within a DRX cyclefor Device-to-Device, D2D, operation, the first time period and thesecond time period being non-overlapping time periods; and perform a D2Doperation during the first time period and a cellular operation duringthe second time period.
 2. The wireless device of claim 1, wherein thedetermination of the first time period and the second time periodcomprises one or more of the following: determining the first timeperiod and the second time period based on a predefined rule;determining the first time period and the second time periodautonomously; determining the first time period and the second timeperiod based on a message received from another node; determining thefirst time period and the second time period based on a configurationreceived via higher-layer signaling; adapting one or both of the firsttime period and the second time period; and configuring one or both ofthe first time period and the second time period.
 3. The wireless deviceof claim 1 wherein the first time period is one of a DRX ON duration anda DRX OFF duration during a DRX cycle, and the second time period isanother one of the DRX ON duration and the DRX OFF duration during thesame DRX cycle.
 4. The wireless device of claim 1 wherein the wirelessdevice is configured with a DRX cycle for downlink cellular operation,the first time period is a DRX ON duration of the DRX cycle for downlinkcellular operation, and the second time period is a DRX OFF duration ofthe DRX cycle for downlink cellular operation.
 5. The wireless device ofclaim 1 wherein the wireless device is configured with a common DRXcycle for both downlink cellular operation and D2D operation, the firsttime period is one of a DRX OFF duration and a DRX ON duration of thecommon DRX cycle, and the second time period is another one of the DRXON duration and the DRX OFF duration of the common DRX cycle.
 6. Thewireless device of claim 5 wherein the first time period is the DRX ONduration of the common DRX cycle, and the second time period is the DRXOFF duration of the common DRX cycle.
 7. The wireless device of claim 1wherein the first time period is a first DRX ON duration of a first DRXcycle, and the second time period is a second DRX ON duration of asecond DRX cycle.
 8. The wireless device of claim 1 wherein the firsttime period and the second time period are non-overlapping time periodswithin a DRX ON duration of a DRX cycle.
 9. The wireless device of claim8 wherein an amount of time during the DRX ON duration used for thefirst time period and an amount of time during the DRX ON duration usedfor the second time period are network configured.
 10. The wirelessdevice of claim 8 wherein an amount of time during the DRX ON durationused for the first time period and an amount of time during the DRX ONduration used for the second time period are decided by the wirelessdevice autonomously.
 11. The wireless device of claim 1 wherein thefirst time period and the second time period are configured such thatthe first time period and the second time period are separated in timeby a time, t, for which one or both of the following condition holds:Tmin≦t≦Tmax, where Tmin is a predefined minimum amount of time and Tmaxis a predefined maximum amount of time.
 12. The wireless device of claim1 wherein the first time period and the second time period areconfigured such that a predefined order is maintained between the firsttime period and the second time period.
 13. The wireless device of claim1 wherein the D2D operation performed during the first time period isreception of D2D signals, and the cellular operation performed duringthe second time period is reception of downlink cellular signals. 14.The wireless device of claim 1 wherein the first and second time periodsare within the same DRX cycle.
 15. The wireless device of claim 14wherein the DRX cycle is one of a downlink cellular DRX cycle and acommon DRX cycle for both downlink cellular and D2D operation.
 16. Thewireless device of claim 1 wherein the first and second time periods arewithin different DRX cycles.
 17. The wireless device of claim 16 whereineach of the different DRX cycles is one of a downlink cellular DRX cycleand a common DRX cycle for both downlink cellular and D2D operation. 18.A method of operation of a wireless device enabled to operate in acellular communications network, comprising: determining a first timeperiod within a Discontinuous Reception, DRX, cycle for cellularoperation and a second time period within a DRX cycle forDevice-to-Device, D2D, operation, the first time period and the secondtime period being non-overlapping time periods; and performing a D2Doperation during the first time period and a cellular operation duringthe second time period.
 19. The method of claim 18 wherein the firsttime period is one of a DRX ON duration and a DRX OFF duration during aDRX cycle, and the second time period is another one of the DRX ONduration and the DRX OFF duration during the same DRX cycle.
 20. Anetwork node of a cellular communications network, comprising: aprocessing module; and a memory module storing instructions executableby the processing module whereby the network node is operable to:determine one or more Discontinuous Reception, DRX, sharing rules for awireless device, the one or more DRX sharing rules definingnon-overlapping time periods within one or more DRX cycles comprising afirst time period to be used by the wireless device for cellularoperation and a second time period for Device-to-Device, D2D, operationand the one or more DRX sharing rules comprise at least one of the groupconsisting of: a rule that the first time period is a first DRX ONduration of a first DRX cycle and the second time period is a second DRXON duration of a second DRX cycle; a rule that the first time period andthe second time period are non-overlapping time periods within a DRX ONduration of a DRX cycle; and a rule that the first time period and thesecond time period are configured such that the first time period andthe second time period are separated in time by a time, t, for which oneor both of the following condition holds:Tmin≦t≦Tmax, where Tmin is a predefined minimum amount of time and Tmaxis a predefined maximum amount of time; and configure the wirelessdevice with the one or more DRX sharing rules.
 21. The network node ofclaim 20 wherein, via execution of the instructions by the processingmodule, the network node is further operable to dynamically adapt theone or more DRX sharing rules for the wireless device.
 22. The networknode of claim 20 wherein the one or more DRX sharing rules furthercomprise a rule that the first time period is one of a DRX ON durationand a DRX OFF duration during a DRX cycle and the second time period isanother one of the DRX ON duration and the DRX OFF duration during thesame DRX cycle.
 23. The network node of claim 20 wherein the one or moreDRX sharing rules comprise the rule that the first time period is thefirst DRX ON duration of the first DRX cycle and the second time periodis the second DRX ON duration of the second DRX cycle.
 24. The networknode of claim 20 wherein the one or more DRX sharing rules comprise therule that the first time period and the second time period arenon-overlapping time periods within a DRX ON duration of a DRX cycle.25. The network node of claim 20 wherein the one or more DRX sharingrules comprise the rule that the first time period and the second timeperiod are configured such that the first time period and the secondtime period are separated in time by the time, t, for which one or bothof the following condition holds:Tmin≦t≦Tmax, where Tmin is the predefined minimum amount of time andTmax is the predefined maximum amount of time.
 26. The network node ofclaim 20 wherein the one or more DRX sharing rules further comprise arule that the first time period and the second time period areconfigured such that a predefined order is maintained between the firsttime period and the second time period.
 27. The network node of claim 20wherein the network node determines the one or more DRX sharing rulesfor the wireless device based on one or more criteria, the one or morecriteria comprising at least one of a group consisting of: an amount ofcellular and/or D2D traffic; battery life and/or power consumption ofthe wireless device; DRX cycle length; length of ON duration; occasionsof D2D operations; receiver capability of the wireless device; andactivity state of the wireless device.
 28. A method of operation of anetwork node of a cellular communications network, comprising:determining one or more Discontinuous Reception, DRX, sharing rules fora wireless device, the one or more DRX sharing rules definingnon-overlapping time periods within one or more DRX cycles comprising afirst time period to be used by the wireless device for cellularoperation and a second time period for Device-to-Device, D2D operationand the one or more DRX sharing rules comprise at least one of the groupconsisting of: a rule that the first time period is a first DRX ONduration of a first DRX cycle and the second time period is a second DRXON duration of a second DRX cycle; a rule that the first time period andthe second time period are non-overlapping time periods within a DRX ONduration of a DRX cycle; and a rule that the first time period and thesecond time period are configured such that the first time period andthe second time period are separated in time by a time, t, for which oneor both of the following condition holds:Tmin≦t≦Tmax, where Tmin is a predefined minimum amount of time and Tmaxis a predefined maximum amount of time; and configuring the wirelessdevice with the one or more DRX sharing rules.